Bennett's defeat marks the first time a sitting Senator has lost in an intraparty fight since 2006 when Sen. Joe Lieberman was ousted by wealthy businessman Ned Lamont in the Democratic primary. Lieberman went on to run and win as an independent; under state law Bennett cannot pursue that course.
It also marks the first major victory for the conservative wing of the Republican party, which has organized itself under the banner of the Tea Party movement to protest what they believe to be a government run amok.
Bennett, a reliable conservative on most issues, had repeatedly expressed exasperation at his predicament -- insisting that the ideological right's issues with him were less about his record and more about the tone he struck during the partisan warfare in Washington.
Actually, this is the second time in recent years something like this has happened in Utah -- Jason Chaffetz's primary defeat of arch-conservative six-term Rep. Chris Cannon (R) on grounds of insufficient conservatism had a very similar ring.